Yorke was responding to criticisms from author and journalist Hannah Pool, who claimed that writers turned Lucas into a killer with little reasoning.
Pool had suggested: "When Lucas first appeared and as a man of the cloth, I was really interested because religion plays a big part in many black communities.
"But then he started killing people and my heart sank. I thought, 'When you have so few black male characters, is this really the best you can do?'
"EastEnders very nearly had a credible, working black family and they ruined it by making Lucas a murderer. I feel that a whole family has been written off."
Yorke said in response: "If you look at the history of Afro-Caribbean men on British TV, the early days saw them almost universally cast as 'villains'.
"In the more enlightened '80s things started to change, and in a bid to correct that bias they tended to mean 'boring'."
He continued: "When Gary Beadle was cast as Paul Trueman, he actually hugged me and said, 'Thank God I can be a bastard!' When we discussed Lucas's storyline with Don Gilet, he was ecstatic.
"It struck me then how ironic it was that the good intentions of the white liberal media had the effect of denying black men interesting roles.
"While you have to be careful about representation, if all actors aren't allowed equal rights to play whatever stories come up, then a whole new type of far more insidious racism comes into place."
> BBC defends 'EastEnders' Lucas storyline